I think I’m going to say “no” to Joe Scarborough’s question:
Will Twitter and the Internet prevent a Tiananmen Square-styled crackdown in Tehran? Will technology trump theocracy?
I think there’s no doubt that the growth of modern information technology facilitates organizing anti-regime protests in authoritarian states. I don’t think you need to attribute that all to Twitter, as such, but the overall pattern is clear. Organizing mass demonstrations requires a lot of communication, and things that make communication easier make organizing easier.
But when you have your mass protests, you still have the key question. Do the security services just kill a bunch of people (Tiananmen)? Does the regime blink and surrender (Velvet Revolution)? Does the regime attempt surrender, only to be undercut by a hardline coup (USSR, 1991)? Does the regime attempt to resist, only to be undone by a coup (Romania)? Information technology doesn’t seem to me to have anything to do with this. It all has to do with internal regime politics, and the attitudes of the people leading and serving in the security forces.